To connect portable or remote network end devices to the Internet of Things (IoT), or to control machines remotely using machine-to-machine communication (M2M), a mobile radio connection for data exchange via the cloud is a good option.
However, this option presents hurdles for the developer, such as determining which wireless networks can support the required data throughput worldwide and which protocols the wireless modem must be able to handle. System scalability, data security, cost, time to market, and the acquisition and operating costs incurred by the user must also be considered.
IoT and M2M applications
This article briefly explains what LTE Cat 1 offers developers of IoT and M2M applications. It then introduces radio modules from u-blox's LARA-R6 series that provide universal connectivity and reliable performance.
The article concludes by showing how developers can use an evaluation board (EVB) to configure and control the modules via AT commands and generate AT command strings via library functions.
LTE Cat 1 compared to LTE Cat 1bis, LTE Cat M, and LTE Cat NB
While LTE cellular radio now achieves gigabit transmission rates, low-power, wide-area (LPWA) protocols like LTE Cat 1, LTE Cat 1bis, LTE Cat M, and LTE Cat NB are designed to be particularly efficient in terms of energy consumption, network resources, and cost. This is critically important for IoT devices.
Providing up to 20 megahertz (MHz) channel bandwidth in full duplex, LTE Cat 1 achieves download data rates of up to 10 megabits per second (Mbps) and upload data rates of up to 5 Mbps. Two antennas enable receiver (Rx) diversity for better performance (Table 1). LTE Cat 1bis uses a single antenna.
LTE Cat 1 mobile radio for global availability
These modules are an excellent solution for global/multi-regional coverage and come in a small LGA
u-blox's LARA-R6 series is comprised of robust cellular radio modules designed for the radio access technology (RAT) LTE Cat 1 frequency division duplex (FDD) and time division duplex (TDD) standards.
They support 3G UMTS/HSPA and 2G GSM/GPRS/EGPRS as a fallback solution. These modules are an excellent solution for global/multi-regional coverage and come in a small LGA form factor measuring 26 x 24 millimeters (mm).
Features and Capabilities
Equipped with versatile interfaces, a wide variety of features, and multiband and multimode capabilities, LARA-R6 modules are suitable for applications that require medium data speed, seamless connectivity, excellent coverage, and low latency.
Such applications include asset tracking, telematics, remote monitoring, alarm centers, video surveillance, connected health, and point-of-sale terminals.
Reliable performance
Programmers can take advantage of the embedded IoT protocols and security features
All modules support Rx diversity for reliable performance in difficult coverage conditions or when voice-over LTE (VoLTE) is required.
Programmers can take advantage of the embedded IoT protocols (LwM2M, MQTT) and security features (TLS/DTLS, secure update, and secure boot) to implement various functions, including device management, remote device control, and secure firmware over-the-air (FOTA) updates.
Three regional variants
The LARA-R6 series supports LTE Cat 1 according to 3GPP Release 10 and achieves global coverage with three regional variants:
- The LARA-R6001-00B (data and voice) and LARA-R6001D-00B (data only) modules support 18 LTE FDD/TDD frequency bands plus 3G/2G fallback for global connectivity.
- The LARA-R6401-00B (data and voice) and LARA-R6401D-00B (data only) modules provide an ideal LTE Cat 1 solution for North America, supporting LTE bands from AT&T, FirstNet, Verizon, and T-Mobile.
- The LARA-R6801-00B (data and voice) and LARA-R6801D-01B (data only) modules are designed for deployments in the following regions: Europe and the Middle East (EMEA), Asia Pacific (APAC), Japan (JP), and Latin America (LATAM) (Figure 1).
LARA-R6 special features at a glance
LARA-R6 modules integrate a cellular baseband processor with external interfaces, an RF transceiver with amplifiers and filters, memory, and a power management unit (Figure 2).
The RF transceiver operates in the frequency bands 700 MHz, 800 MHz, 850 MHz, 900 MHz, 1.7 GHz, 1.8 GHz, 1.9 GHz, 2.1 GHz, and 2.6 GHz. All data transfer protocols of the cellular baseband processor can be controlled and configured via AT commands using the external UART and USB interfaces.
Protocols
- Dual stack IPv4 and IPv6
- Embedded TCP/IP, UDP/IP, FTP, and HTTP
- Embedded MQTT and MQTT-SN
- Embedded LwM2M
- eSIM and Bearer Independent Protocol (BIP)
Peak transmission powers
An excellent antenna sensitivity of less than -100 dBm, corresponding to signal powers of less than 0.1 pW
LARA-R6 modules require a supply voltage of 3.1 to 4.5 volts and have an idle current consumption of around 1.1 milliamperes (mA). In 2G operation, individual TDMA time slots can reach peak transmission powers of over 33 decibels referenced to 1 milliwatt (mW) (dBm) (> 2.0 watts), and all other RAT reach levels of over 24 dBm (> 0.25 watts).
An excellent antenna sensitivity of less than -100 dBm, corresponding to signal powers of less than 0.1 picowatts (pW), enables stable radio connections at the edge of the mobile network.
Evaluating and programming
The quickest way to start evaluating and programming a LARA-R6 module is to use an R6 EVB (EVK-R6) and a plug-in LARA-R6 adapter board (ADP-R6) for the corresponding region.
For example, the EVK-R6001-00B for global applications includes the plug-in adapter board ADP-R6001-00B (voice + data) and a GNSS adapter board (Figure 3).
Voice and data transmission
EVK-R6801-00B for EMEA/APAC/JP/LATAM includes the ADP-R6801-00B adapter
The EVK-R6401-00B variant for North America includes the ADP-R6401-00B adapter, while the EVK-R6801-00B for EMEA/APAC/JP/LATAM includes the ADP-R6801-00B adapter.
The three adapter boards already mentioned for voice and data transmission are also available separately, as are versions for data transmission only, including the ADP-R6401D-00B (North America) and ADP-R6001D-00B (global).
R6 adapter board
The R6 adapter board extends the LARA-R6 module with two antennas and two MiniUSB connectors. The R6 EVB adds a GNSS module, a SIM card slot, additional plug-in connections, jumpers, switches, and a power supply to the module peripherals (Figure 4).
Each kit contains one EVB with an attached LTE Cat 1 LARA-R6 adapter board and a GNSS module from u-blox, one USB cable, two LTE mobile radio antennas, a GPS/GLONASS antenna, and a power supply unit.
Commissioning of the EVK
The EVK-R6 kit from u-blox simplifies the evaluation of multimode LTE Cat 1 / 3G / 2G cellular modules
The easy-to-use, powerful EVK-R6 kit from u-blox simplifies the evaluation of multimode LTE Cat 1 / 3G / 2G cellular modules.
A Windows PC with the LARA-R6 USB driver installed controls the LARA-R6 modem via the USB connector and simplifies the connection setup via the system settings. To get started, the developer needs to:
- 1) Insert the SIM card and connect both cellular antennas and the GNSS antenna.
- 2) Carefully configure the jumpers and switches of the EVK.
- 3) Apply the supply voltage and turn on the main switch SW400 on the EVB.
- 4a) For operation as a low data rate modem via the “Main UART” interface, connect the PC to the MiniUSB jack J501 or RS232 jack J500 on the EVK.
b) For operation as a low data rate modem via “Two UARTs”, connect the PC to the cellular USB jack J201 interface on the ADP.
c) For operation as a high data rate modem via “Native Cellular USB”, connect the PC to the MiniUSB jack J105 on the ADP.
- 5) Press the Cellular Power-On button SW302 on the EVB.
- 6) Run a terminal application software (such as m-center), go to the COM port setup menu, choose the AT port corresponding to 4a, 4b, or 4c, and set these values: Data rate: 115,200 bps; Data bits: 8; Parity: N; Stop bits: 1.
For more details, refer to the EVK-R6_UserGuide_UBX-21035387. The m-center tool helps evaluate, configure, and test u-blox cellular products, and it includes an AT command terminal.
Simple Internet connection using a Windows PC
By connecting a Windows PC to the EVK, the user can establish a wireless Internet connection in two ways:
- A low-speed packet data connection: This uses the TCP/IP stack of the Windows PC via the UART interface of the LARA-R6 module. The PC and EVK are connected according to method 4a. The developer must select Phone and Modem > Modems > Add using the Windows Control Panel. The next step is to pick the “Don’t detect my modem” checkbox, select “Standard 33.6 kbps Modem”, and allocate a COM port. If necessary, the developer can add Properties > Advanced > Extra initialization commands.
- A high-speed packet data connection: This accesses the Internet using the TCP/IP stack of the Windows PC via the cellular native USB interface of the LARA-R6 module. The PC and EVK are connected according to method 4c. The developer must select Network and Sharing Center > Set up a new connection or network via the Windows Control Panel and click “Connect to the Internet”. The next step is to select “Dial-up” and one of the AT USB Ports. The final step is to enter dial-up parameters (Dial-in number, provider name, user ID, and password).
Registering the SIM card with the mobile operator
Once the SIM card and MNO parameter are configured, the cellular module automatically registers itself on the cellular network after power-on. If there is a problem, the registration can be checked manually using the AT commands shown in Table 2.
Communication to the remote HTTP server via AT command
Sixteen application examples, including ping tests, registration, packet switch, SMS, GNSS, and IoT cloud
The GitHub repository “Firechip_u-blox_LARA-R6_Arduino_Library” contains an extensive library of AT commands for the LARA-R6 modules, written in C++ for Arduino controllers.
Sixteen application examples, including ping tests, registration, packet switch, SMS, GNSS, and IoT cloud, provide suggestions for custom code structures.
ThingSpeak
AT commands can also send requests to a remote HTTP server during an active connection, receive the server response, and store that response transparently in the local file system. The supported methods are HEAD, GET, DELETE, PUT, POST file, and POST data.
The Lara_R6_Example9 sends random temperatures to the RemoteHTTP-Server ThingSpeak.com using HTTP POST or GET. ThingSpeak is an IoT analytics platform service by MathWorks that helps to aggregate, visualize, and analyze live data streams in the cloud. Table 3 shows the syntax of the HTTP command “POST data.”
This example can be programmed on an Arduino host controller, which controls the LARA-R6 module on an EVK board via AT commands. Additionally, a configured SIM card is required.
Random temperature measurement
The C++ main program generates a random temperature value, forms the cloud-specific data string
The programmer must create a ThingSpeak user account and set field 1 for the random temperature measurement value via the menu item Channels > My Channels > New Channel. The corresponding "Write API Key" is entered in the main program.
The C++ main program generates a random temperature value, forms the cloud-specific data string, and calls the library function every 20 seconds.
Generate the AT command string calling library functions
The library header “Firechip_u-blox_LARA-R6_Arduino_Library.h” forwards the function call sendHTTPPOSTdata to the library procedure “Firechip_u-blox_LARA-R6_Arduino_Library.cpp”, where the fully formatted AT command string is generated and sent.
The library procedure uses the passed parameters of the function and additionally declared variables from the library header to generate the complete HTTP command string according to Table 3. Finally, the LARA-R6 modem sends the resulting AT command string to the ThingSpeak remote HTTP server.
Conclusion
For the global networking of low-power IoT and M2M applications, LTE Cat 1 multi-mode radio modules from the LARA-R6 series are efficient and cost-effective.
As shown, developers have ready access to all interfaces using the EVK and can easily configure and control the protocols and functions of the module via AT commands. This provides simple options for operating as a PC modem, sending data to the cloud, and generating AT command strings via library functions.
